Pinching and Cutting Device for a Flat Knitting Machine

Abstract

The invention relates to a device (3) for pinching and cutting yarns for a flat knitting machine, said machine, said machine comprising at least one needle board (1) on which a plurality of needles are arranged, said device comprising a plurality of hooks (6) capable of grasping at least one yarn and moving between an idle position and a gripping position, said device being configured to be fastened to one of the ends of said needle board such that said device, when fastened to the needle board of the machine, extends in the plane of said needle board.

Description

TECHNICAL FIELD OF THE INVENTION

The invention relates to the field of flat knitting machines. The invention in particular pertains to a device for pinching and cutting the knitting yarns. The invention also relates to a flat knitting machine comprising such a device.

BACKGROUND OF THE INVENTION

In a flat knitting machine, the knitting yarns are distributed to the needles of the needle boards using yarn guides. When knitting with knitting yarns, it is often necessary to pinch and cut the knitting yarns.

In order to allow pinching and cutting of the knitting yarns, a device is known from KR 1020050014665 for pinching and cutting the yarns for a flat knitting machine. This device is activated using a carriage that moves above the needle boards. However, the need to use a carriage to activate this device causes many constraints that result in a non-negligible decrease in the productivity of the knitting machine.

BRIEF DESCRIPTION OF THE INVENTION

A first aim of the invention is to provide a device for pinching and cutting yarns for a flat knitting machine that makes it possible to grasp, or pinch, yarns and cut them.

A second aim of the invention is to provide a device for pinching and cutting yarns for a flat knitting machine that does not require the use of a carriage, which traditionally moves above needle boards of the machine, to activate it.

A third aim of the invention is to provide a pinching and cutting device in which each hook of the device can be actuated individually and independently of the others.

A fourth aim of the invention is to provide a pinching and cutting device for a flat knitting machine that is inexpensive to manufacture.

A fifth aim of the invention is to provide a pinching and cutting device for a flat knitting machine that is not bulky, in particular that does not clutter the area situated between the needle boards of the machine.

A sixth aim of the invention is to provide a pinching and cutting device that is configurable so that it can be resized as needed.

These aims are achieved using a device for pinching and cutting yarns for a flat knitting machine, said machine comprising at least one needle board on which a plurality of needles are arranged, said device comprising a plurality of hooks capable of grasping at least one yarn and moving between an idle position and a pinching and cutting position, said device being configured to be fastened to one of the ends of said needle board such that said device, when fastened to the needle board of the machine, extends in the plane of said needle board, said device comprising activating means making it possible to move the hooks of said device independently of one another, said activating means being kinematically connected to driving means comprising at least one motor.

Because the pinching and cutting device described above can be fastened in the extension of the needle board(s) of a flat knitting machine, it therefore does not clutter the space situated between the needle boards of the machine. It also makes it possible to move a plurality of hooks independently of one another.

According to one feature of the invention, said driving means may consist of a first electric motor and a second electric motor.

The pinching and cutting device according to the invention can therefore be limited to the use of only two electric motors. The production costs of such a device are thereby minimized.

According to another feature, said activating means may comprise connecting means, a first set of activation bars and a second set of activation bars, said connecting means being configured and arranged so as to kinematically connect said driving means with said first set of activation bars and said second set of activation bars.

According to another feature, said connecting means can be configured and arranged so as to be able to move all of the activation bars of said first set simultaneously and to move all of the activation bars of said second set simultaneously.

According to the invention, the driving means can be configured and arranged so as to be able to drive the activation bars of said first set independently of the activation bars of said second set.

According to the invention, said connecting means can comprise a first axle provided with at least one first toothed wheel.

According to the invention, said connecting means may comprise a second axle provided with at least one second toothed wheel.

According to the invention, the first toothed wheel can mesh with a rack of an activation bar of said first set.

According to the invention, said second toothed wheel can mesh with a rack of an activation bar of said second set.

According to another feature of the invention, each of the activation bars of said first set can be provided with a lever arranged such that said lever can move between an active position and an inactive position.

According to the invention, said lever can be provided with a first pilot point.

According to the invention, said lever can be provided with a second pilot point.

According to the invention, each of the activation bars of said second set can comprise a cam path extending over at least part of its length.

According to the invention, said cam path can comprise at least one protuberance.

According to the invention, each of said hooks can include a notch.

According to the invention, said device can comprise detection means for determining the position of the hooks of the device.

A flat knitting machine according to the invention comprises at least one device as described above.

DESCRIPTION OF THE FIGURES

Other features and advantages of the invention will emerge from reading the following description, done in reference to the appended drawings, in which:

FIG. 1 shows a needle board of a flat knitting machine provided with a pinching and cutting device according to the invention;

FIG. 2A shows a top perspective view of the pinching and cutting device according to the invention;

FIG. 2B shows a bottom perspective view of the pinching and cutting device according to the invention;

FIG. 3 shows a bottom perspective view of the pinching and cutting device according to the invention;

FIGS. 4A and 4B show detailed bottom views of the pinching and cutting device according to the invention;

FIG. 5A shows an activation bar of the first set;

FIG. 5B shows an activation bar of the second set;

FIG. 5C shows a hook of the device;

FIGS. 6A and 6B show two phases of the process making it possible to move the lever from its active position to its inactive position;

FIGS. 7A-7E show the complete process making it possible to move the hook from its pinching and cutting position to its gripping position, and vice versa.

DETAILED DESCRIPTION

FIG. 1 shows a needle board 1 of a flat knitting machine. Fastened on the needle board 1, on the right in the figure, is a traditional pinching and cutting device 2 that is used to pinch certain threads during implementation of a knitting method. Traditionally, this device 2 is actuated by the carriage (not shown), which moves above the needle boards of the machine during the implementation of the knitting method.

Fastened at the other end of the needle board, on the left in figure, is a pinching and cutting device 3 according to the invention. As shown in the figure, when the pinching and cutting device 3 according to the invention is fastened to the needle board 1 of the knitting machine, the latter is located in the plane of the needle board. It should be noted at this stage that the pinching and cutting device 3 according to the invention can be fastened to any end of the needle board 2 and any needle board of a flat knitting machine. It should also be noted that, owing to its positioning, the pinching and cutting device according to the invention does not clutter the space situated between the needle boards of the machine. Thus, although FIG. 1 is limited, for clarity reasons, to showing a single needle board, it is implied that one skilled in the art will understand that the pinching and cutting device 3 according to the invention can be used in a flat knitting machine comprising more than one needle board.

FIGS. 2A and 2B show the pinching and cutting device 3 according to the invention in top view and bottom view, respectively.

According to the preferred embodiment, the device 3 comprises two electric motors 4 and 5 that make it possible to actuate, as will be described below, the hooks 6 of the device. It should be noted at this stage that, in light of the fact that only two electric motors are necessary, the device 3 according to the invention is therefore less expensive to manufacture.

It will also be noted that FIGS. 2A and 2B, as well as the preceding description, indicate the presence of two motors 4 and 5. Alternatively, it is, however, possible to consider using a single motor provided with two output shafts and means for making those two shafts move independently of one another.

The device 3 according to the invention comprises a plurality of notches 6 that are capable of moving between an idle position (FIG. 7A) and a gripping position (FIG. 7C), in which said hooks are capable of grasping a yarn provided by a yarn guide of the knitting machine and pinching it to next be able to cut it.

The number of hooks present in the device as shown in FIGS. 2A and 2B is sixteen. Alternatively, a larger or smaller number of hooks may be considered, and the pinching and cutting device may therefore be dimensioned to include a larger or smaller number of hooks 6 as needed. The device further comprises cases 7 making it possible to protect the activating mechanism located inside the device 3 from dust.

FIG. 3 shows a perspective bottom view of the pinching and cutting device 3 according to the invention when the protective cases 7 have been removed. As shown in the figure, the output pinion 8 of the motor 4 meshes with the toothed wheel 9 of the first axle 10, which will be called “lever axle”. Similarly, the output pinion 11 of the motor 5 meshes with a toothed wheel 12 of a second axle 13, which will be called “selector axle”. Thus, the rotation of the shaft of a motor causes the rotation of the axle to which it is connected.

The first axle 10, i.e., the lever axle, and the second axle 13, i.e., the selector axle, are provided with a plurality of toothed wheels 14 which, as will be seen below, each mesh with an activation bar 15 provided, over at least part of its length, with a rack. The number of toothed wheels 14 corresponds to the number of hooks 6 of the device 3, and the number of activation bars 15 therefore corresponds to twice the number of hooks of the device.

FIG. 4B shows a detailed view of the parts 16 of the pinching and cutting device 3 according to the invention indicated in FIG. 4A.

FIG. 4B shows that the toothed wheels 140 of the lever axle 10 mesh with the activation bars 150, via the racks with which they are provided, while the toothed wheels 141 of the selector axle 13 mesh with the activation bars 151, via the racks with which the latter are provided. The operation of these connections will be described in more detail in reference to FIGS. 7A-7E. The lever axle 10 therefore acts on the activation bars 150 engaged with it while the selector axle 13 acts on the activation bars 151 engaged with the latter.

It will therefore be noted that the device in reality comprises a first set of activation bars 150 and a second set of activation bars 151. As explained in the rest of the description, the activation bars of the first set 150 make it possible to interact directly with the hooks 6 in order to move the latter. The second set of activation bars 151 makes it possible, as will be explained below, to select one or the other of the hooks 6.

The use of the motors 4 and 5 and the axles 10 and 13 provided with toothed wheels 14 meshing with the racks of the activation bars 150 and 151 is, however, only one possible embodiment. In fact, it is alternatively possible to consider substituting other means making it possible to actuate the activation bars 150 and 151 in place of the motors 4 and 5, the axles 10 and 13 and the toothed wheels 14. It is for example possible, in this respect, to consider having each activation bar be connected to a linear motor, the latter making it possible to translate the activation bar to which it is connected.

FIG. 5A shows a perspective view of one of the activation bars of the first set of activation bars 150. Each activation bar of this set 150 is provided with a rack, extending over at least part of its length, and a lever 51, or selector, that can pivot around an axle 52 between an inactive position (shown in the figure and indicated by the number 0) and an active position (indicated by the number 1). The lever 51 is provided with a first pilot point 53 designed to slide, as will be described below, in a specific cam path 55 provided in the adjacent activation bar belonging to the second set of activation bars 151 (FIG. 5B) that is activated by the selector axle 13. This cam path is provided with a protuberance 56 which, in contact with the pilot point 53, causes the lever to go from its inactive position to its active position. Alternatively, the cam path may be provided with a plurality of protuberances.

It should be noted that each activation bar of the second set of activation bars 151 of the device has a different cam path inasmuch as, for each activation bar of the second set of activation bars 151, the positioning of the protuberance 56 is different.

The lever 51 (FIG. 5A) is further provided with a second pilot point 54 designed to interact with a selector notch 61 of the hook (shown in FIG. 5C).

FIGS. 6A and 6B show, for one of the hooks of the device, the process making it possible to move the hook from its pinching and cutting position, in which the book is capable of pinching a yarn, to its gripping position, in which the hook is capable of grasping a yarn provided by a yarn guide.

In FIG. 6A, the activation bar of the second set of activation bars 151 is moved backward in the direction of the arrow A via a rotational movement of the selector axle 13. The figure shows the position of the pilot point 53 of the lever 51 of the activation bar of the first set of activation bars 150 in the cam path 55. The lever is in the inactive position and the hook is in the idle position.

FIG. 6B shows the continuation of the process when the activation bar of the second set of activation bars 151 is advanced toward the arrow B, following the rotation of the selector axle 13. The figure in particular shows the moment where the pilot point 53 encounters the protuberance 56 of the cam path. When the pilot point 53 encounters the protuberance 56, the lever switches into the active position. This contributes to causing the pilot point 54 of the lever to enter the selection notch 61 of the hook. The hook 6 is thus selected, and a synchronized movement of the activation bars of the first set of activation bars 150 and the second set of activation bars 151 causes, through the appropriate rotation of the axles 10 and 13, the hook to move from its idle position to its gripping position.

FIGS. 7A-7E show the details of the method for selecting and deselecting one of the hooks of the pinching and cutting device 3 according to the invention. Each figure shows a left view and a right view for better understanding.

In FIG. 7A, the lever 52 is in the inactive position.

In FIG. 7B, the rotation of the axle 13 drives the movement of the activation bar of the second set of activation bars 151 in the direction of the arrow C. The pilot point 53 that slides in the cam path 55 encounters the protuberance 56. The lever 51 then pivots into the active position and the pilot point 54 becomes housed in the selection notch 61 of the hook 6. The hook 6 is then engaged with the lever 51.

In FIG. 7C, the lever 51 being engaged with the hook 6, the axles 10 and 13 are actuated simultaneously in the same direction of rotation. A synchronized rotation of the axles 10 and 13 drives the synchronized movement of the activation bar of the first set of activation bars 150 and the activation bar of the second set of activation bars 151. The pilot point 53 therefore remains at the protuberance 56 and the pilot point 54 thus remains in the selection notch 61. The hook 6 thus moves in the direction of the arrow B toward its gripping position, in which it can grasp a yarn brought by a yarn guide.

FIG. 7D shows the process making it possible to return the hook from its gripping position to its idle position. The axles 10 and 13 are actuated simultaneously in the opposite direction, with the result that the activation bar of the first set of activation bars 150 and the activation bar of the second set of activation bars 151 move in the direction of the arrow A. The lever being in the active position and the pilot point 54 remaining in the selection notch 61 of the hook 6, the hook therefore also moves in the direction of the arrow B. The hook thus goes from its gripping position to its idle position.

FIG. 7E shows the deselection phase of the hook 6. The axle 13 moves the activation bar of the second set of activation bars 151 such that the pilot point 53 leaves the location of the protuberance 56. The lever 51 switches into the inactive position and the pilot point 54 leaves the selection notch 61 of the hook 6. The hook 6 is then no longer engaged with the lever 51 at that moment.

As described above, the hook can therefore be moved between idle position and a gripping position in which the hook is capable of grasping, in other words pinching, a yarn brought by a yarn guide of the machine. FIGS. 7A-7E show that each hook is provided with at least one sharp edge 6′. Thus, when a yarn previously brought by a yarn guide is grasped by a hook 6, a withdrawal of the yarn applied by the yarn guide automatically causes cutting of the yarn using the sharp edge 6′. Alternatively, when the yarn is blocked by the yarn guide and grasped by a hook, the passage of the hook from its gripping position to its idle position causes cutting of the yarn. The device according to the invention is therefore capable of grasping, or pinching, a yarn and cutting it.

The phases of the process shown above are of course implemented for each of the hooks of the device. The pinching and cutting device according to the invention therefore makes it possible to select and deselect the hooks of the device independently of one another.

The device further comprises detection means making it possible to determine the position of the hooks and racks of the device at any time. These detection means (not shown) comprise at least one optical fiber and at least one optical sensor that are positioned at the activation bars. These means make it possible, inter alia, to determine whether one of the levers 51 of the device is in the active position and whether the hooks are in the gripping position or the inactive position.

These detection means are connected and interact with hardware and software means of the flat knitting machine on which the pinching and cutting device according to the invention is fastened. The detection means thus make it possible, following a power outage, for example, to determine, when power is restored to the knitting machine, the position of the hooks (gripping or idle), and the position of the levers (active or inactive) of the activation bars of the first set of activation bars 150 of the pinching and cutting device according to the invention.

Claims

1. A device for pinching and cutting yarns for a flat knitting machine, said machine comprising at least one needle board on which a plurality of needles are arranged, said device comprising a plurality of hooks capable of grasping at least one yarn and moving between an idle position and a pinching and cutting position, said device being configured to be fastened to one of the ends of said needle board such that said device, when fastened to the needle board of the machine, extends in the plane of said needle board, and wherein said device comprises activating means making it possible to move the hooks of said device independently of one another, and wherein said activating means are kinematically connected to driving means comprising at least one motor.

2. The device according to claim 1, wherein said driving means consist of a first electric motor and a second electric motor.

3. The device according to claim 1, wherein said activating means comprise connecting means, a first set of activation bars and a second set of activation bars, said connecting means being configured and arranged so as to kinematically connect said driving means with said first set of activation bars and said second set of activation bars.

4. The device according to claim 3, wherein said connecting means are configured and arranged so as to be able to move all of the activation bars of said first set simultaneously and to move all of the activation bars of said second set simultaneously.

5. The device according to claim 3, wherein the driving means can be configured and arranged so as to be able to drive the activation bars of said first set independently of the activation bars of said second set.

6. The device according to claim 3, wherein said connecting means comprise a first axle provided with at least one first toothed wheel.

7. The device according to claim 3, wherein said connecting means comprise a second axle provided with at least one second toothed wheel.

8. The device according to claim 6, wherein the first toothed wheel meshes with a rack of an activation bar of said first set.

9. The device according to claim 7, wherein the second toothed wheel meshes with a rack of an activation bar of said second set.

10. The device according to claim 3, wherein each of the activation bars of said first set is provided with a lever arranged such that said lever can move between an active position and an inactive position.

11. The device according to claim 10, wherein said lever is provided with a first pilot point.

12. The device according to claim 10, wherein said lever is provided with a second pilot point.

13. The device according to claim 3, wherein each of the activation bars of said second set comprises a cam path extending over at least part of its length.

14. The device according to claim 13, wherein said cam path comprises at least one protuberance.

15. The device according to claim 1, wherein each of said hooks includes a notch.

16. The device according to claim 1, wherein said device comprises detection means for determining the position of the hooks of the device.

17. A flat knitting machine, wherein said machine comprises at least one device according to claim 1.